Hydrogen purity grades

Hydrogen can be purchased in various grades of purity. Research grade is 99.9995%, ultra high purity is 99.999%, high purity is 99.99%, and industrial grade is 99.95%. Of course, the purer the gas, the more expensive it is. 

Most applications, such as fuel cells, will do well with industrial grade hydrogen. Many commercial units operate on this grade, although some manufacturers may require a more pure gas. 

You can purchase your own cylinder with a CGA 350 valve, however, for safety reasons, you will be responsible for having it retested every five years, or according to current regulations. 

The smaller 3111 cylinders are easier to handle. Most people prefer these if their gas consumption does not quickly reduce the contents of the cylinder. We prefer to have several smaller cylinders for experimental purposes, largely due to the ease of handling. 

All cylinders come equipped with a valve specific to the gas in the cylinder, and a cylinder cap. The cylinder cap prevents damage to the cylinder valve while it is in transport, or when it is not in service. If a cylinder were to be tipped over and dropped, damage to the valve at worst could create a dangerous projectile, and a serious fire and explosion hazard. All cylinders in service should be secured by straps or chains, and set on a untippable base, or holding cage, or gas cabinet so that they can not fall or be knocked over. 

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High purity grade boron may be prepared by such hydrogen reduction at high temperatures using a hot filament. 

The R(Ni,Fe,Al)5 hydrogen storage alloy prepared on the base of the commercial cerium ligature (R = Ce, La, Pr, Nd), lanthanum and nickel (both of technical purity grade) has been used in the unit. The composition of the alloy must provide a hydrogen equilibrium pressure of 10 bar over MH at room temperature and above 150 bar at elevated temperatures. 

Derivation Methanol and hydrogen sulfide. Grade 98.0% purity. 

High purity grade chemicals, inorganic refined from technical grades Hydrated alumina silicate powder Hydrazine Hydrochloric acid Hydrocyanic acid Hydrogen sulfide Hydrosulfites Hypophosphites Indium chloride Inorganic acids, except nitric or phosphoric Iodides... 

That is E depends on the sulfuric acid concentration. The rate of the cathodic reaction (13.12) is very slow, because of the very high overpotential of hydrogen evolution on lead electrode of high purity grade. And it is the reaction of hydrogen evolution that exerts the strongest influence on the rate of the self-discharge process, i.e. it practically determines this rate. 

In the electronics industry, a high-purity grade of hydrogen chloride is used as an etchant for semiconductor materials. 

The chemicals used in this study were of the analytical purity grade. Hematite powder was a product of Alfa Division, Danvers, Mass. U.S.A. Standard NBS buffers [6] were i) aqueous solution of KH2PO4 (m = 0.05 mol kg ) and Na2HP04 (m = 0.025 mol kg ), and ii) the solution prepared from potassium hydrogen phtalate (w = 0.025 mol kg ). The pH values of these buffers are tabulated for the wide temperature range. 

Semiconductors. Phosphine is commonly used in the electronics industry as an -type dopant for siUcon semiconductors (6), and to a lesser extent for the preparation of gaUium—indium—phosphide devices (7). For these end uses, high purity, electronic-grade phosphine is required normally >99.999% pure. The main impurities that occur in phosphine manufactured by the acid process are nitrogen [7727-37-9] hydrogen [1333-74-0] arsine [7784-42-17, carbon dioxide [124-38-9], oxygen [7782-44-7], methane [74-82-8], carbon monoxide [630-08-0], and water [7732-42-1]. Phosphine is purified by distillation under pressure to reduce the level of these compounds to <1 ppm by volume. The final product is sold as CYPURE (Cytec Canada Inc.) phosphine. 

Elemental phosphoms from the electrothermal process is a distilled product of high purity and yields phosphoric acid pure enough for most industrial uses without any further treatment. The main impurity is ca 20—100 ppm arsenic present in the phosphoms as the element and in the phosphoric acid as arsenious acid. To remove the arsenic, the phosphoric acid destined for food, pharmaceutical, and some industrial-grade appHcations is treated with excess hydrogen sulfide, filtered, and blown with air to strip out excess H2S. This treatment generally reduces the arsenic content of the phosphoric acid to less than 0.5 ppm. The small amount of filter cake is disposed of in approved chemical landfills. 

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